This invention relates generally to pivot joints and more particularly to preloaded pivot joints that are used in automotive steering linkages.
U.S. Pat, No. 2,009,401 issued to George H. Hufferd and Matthew P. Graham Jul. 30, 1935 discloses a typical preloaded pivot joint for a steering linkage system comprising a housing, a stud and a spring loaded bearing seat inside the housing. The stud rotates and angulates with respect to the housing. The angulation capability is provided by two concentric part spherical members on the inner end portion of the stud that engage a fixed bearing seat in the housing and the spring loaded bearing seat respectively. In this design, the lateral loads of the stud are transferred to the housing by the fixed bearing seat while the axial compression loads are transferred by the spring loaded bearing seat and its associated spring. The pivot joint does not, have any internal mechanism for limiting angulation and so the stud angulates freely until the stud makes metal-to-metal contact with the housing.
U.S. Pat. No. 3,053,556 issued to David E. Klocke and Vincent J Ryszewski Sep. 11, 1962 discloses a preloaded pivot joint for the idler arm of an automotive steering linkage that has a stud that rotates but does not angulate. The Klocke joint comprises a housing, a stud, and a compression spring inside the housing. The Klocke stud has a part spherical portion that engages a fixed bearing seat in the housing under the bias of the compression spring. The Klocke stud has a cylindrical extension at the inner end that is disposed in a thin plastic sleeve housed in a hat-shaped well of the housing cover. The cylindrical extension, the thin plastic bushing and the hat shape of the cover well combine to prevent the stud from angulating any substantial degree so that the stud is limited essentially to rotation. In this design the lateral loads of the stud are taken by the fixed bearing seat, the axial compression loads are taken by the compression spring and the angulation loads are taken by the thin plastic sleeve. However, as indicated above, the thin plastic sleeve virtually eliminates stud angulation.
U.S. Pat. No. 3,945,737 issued to Edward J. Herbenar Mar. 23, 1976 also discloses a preloaded pivot joint for an automotive steering linkage. The Herbenar pivot joint likewise comprises a housing, a stud and a compression spring inside the housing. The stud has a part spherical portion that engages a fixed bearing seat in the housing under the bias of the compression spring. In this instance the compression spring is in the form of a relatively thick bushing of flowable resilient material such as rubber, polyurethane and the like. The resilient bushing is axially split and has a tapered bore. The stud has a tapered extension at the inner end that is disposed in the tapered bore of the resilient bushing so that the resilient bushing performs two functions. The resilient bushing biases the part spherical portion of the stud into engagement with the fixed bearing seat and the resilient bushing also accommodates limited angulation of the stud. In this design the compressive loads of the stud and the angulation loads of the stud are taken by the same member, i.e. the axially split, resilient bushing with the tapered bore. Thus the design inhibits freedom in selecting an axial preload independently of angulation considerations and vice-versa. Moreover the design incorporates a biasing spring that tightens the axially split bushing around the tapered extension of the stud which then resists rotation of the stud.